What is the purpose of the function datumformatieren in the given PHP code?

The purpose of the function datumformatieren in the given PHP code is to format a date string from the format "Y-m-d" to "d.m.Y". To solve this issue, we can create a function called datumformatieren that takes a date string in the format "Y-m-d" as input, converts it to a timestamp using strtotime, and then formats the timestamp into the desired format "d.m.Y" using the date function.

function datumformatieren($date) {
    $timestamp = strtotime($date);
    return date('d.m.Y', $timestamp);
}

// Example usage
$date = '2022-01-15';
$formatted_date = datumformatieren($date);
echo $formatted_date; // Output: 15.01.2022